The objective of these studies is to evaluate factors concerned with regulation of the hypothalamus and pituitary gland in human reproductive events and the possible influence of prolactin on these regulatory phenomena. Studies will be performed in hyperprolactinemic women with and without demonstrable pituitary adenomas to assess: (1) pituitary sensitivity to hypothalamic gonadotropin releasing hormone and estradiol as modified by altered prolactin levels; (2) positive; (3) effects of development of hyperprolactinemia on temporal changes in pituitary and ovarian hormones; (4) morphologic characteristics, secretory capacity, and influence of dopamine on prolactin-producing pituitary tumors; (5) the possible association of antecedent use of oral contraceptive and the development of pituitary microadenomas; and (6) the relative efficacy of microsurgical resection, 2-Bromergocryptine, or no therapy in the management of pituitary microadenomas.